About MSO Calc

A simple, no-nonsense hub of accurate online calculators for finance, health, math and everyday questions — built by an independent developer who got tired of ad-bloated calculator sites.

What This Is

MSO Calc is an independent, self-funded project. The idea is straightforward: people want a quick number — they search for "mortgage calculator," "BMI," or "how many hours between 2pm and 10pm" — and too often what they get is a slow, ad-overlaid page that buries the answer under modals and a newsletter signup.

So this is the calculator site that was missing: every tool loads fast, works on phones, shows the actual formula, and asks for nothing — no signup, no email harvesting, no upsell. The whole thing runs as static HTML. There is no backend and no database, so there is nothing that needs your data.

How the Calculators Are Built

Each calculator is built and tested against edge cases, and each long-form guide is written to explain the method rather than pad it out. Where a formula has tricky edge cases — the Mifflin-St Jeor equation behaves oddly at very low body weights, mortgage amortization rounds in non-obvious ways — the underlying source is checked rather than guessed. The references at the bottom of each guide are there so you can verify the math, not as decoration.

The writing aims for plain English, because most finance and health writing online is unnecessarily mystifying. If a calculator says you can afford a $400,000 house at $5,000/month, the next paragraph should explain what that actually means for a real budget instead of adding more abbreviations.

The Formulas Used

Calculators use standard, well-documented formulas: the amortization formula for loans and mortgages, future-value-of-annuity for investing, Mifflin-St Jeor for BMR (with Harris-Benedict and Katch-McArdle as alternatives where relevant), Heron's formula for triangle area, and the law of sines and law of cosines for general triangle solving. Where there is genuine professional disagreement — most common in health calculations — the alternatives are named and the trade-offs explained.

What This Project Believes

Calculators should be free. The math behind them is hundreds of years old. There is no good reason to gate access.
Privacy is the default, not a feature. Every calculation runs in your browser. The site cannot see your numbers because it does not collect them.
Transparency matters. The formulas are documented. If you spot a math error, report it — every message gets read.
Show, don't just tell. Every result includes context. A BMI of 24 is more useful paired with "you're at the upper end of the healthy range, here's what that means and what doesn't."

How This Site Makes Money

Display advertising — Google AdSense. You'll see ad slots throughout the site. Ads cover hosting, the domain, and the time spent building and maintaining the tools. MSO Calc does not sell user data, run sponsored "calculator recommendations," or take affiliate kickbacks for steering you toward a specific lender, broker or product. If a calculator says renting beats buying, that's the math — no realtor pays for a different answer.

If you really dislike ads, an adblocker works fine here. The site doesn't break, doesn't beg, and doesn't lock you out.

Important Disclaimer

MSO Calc provides educational tools and information. Nothing on this site is financial, tax, legal or medical advice. While calculations are tested and use established formulas, software has bugs and user inputs can be wrong — results may contain errors. Always verify important numbers with a qualified professional before making meaningful decisions. See the full disclaimer.

Get in Touch

Bug report, math error, suggestion, or a request for a calculator that doesn't exist yet? Reach us via the contact page. Everything gets read, and most of it gets a reply.